1. Clinical Immunology, School of Immunity and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, U.K.
2. School of Sport and Exercise Science, College of Life and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, U.K.
3. Mannhein Institute of Public Health, Social and Preventive Medicine (MIPH), University of Heidelberg, D-69120 Heidelberg, Germany